Basionym: Agaricus birrus Fr., Epicrisis Systematis Mycologici: 179 (1838) [MB#463459] Obligate synonyms: - Hylophila birra (Fr.) Quél., Enchiridion Fungorum in Europa media et praesertim in Gallia Vigentium: 99 (1886) [MB#802712] - Hebeloma birrum (Fr.) Sacc. (1887) [MB#237491] - Hebeloma birrum var. birrum (Fr.) Sacc. (1887) [MB#430582] - Hebeloma birrus (Fr.) Sacc., Sylloge Fungorum 5: 794 (1887) [MB#630143] Taxonomic synonyms: - Hebeloma calyptrosporum Gröger, Bull. mens. Soc. linn. Lyon: 125 (1970) [MB#314950] - Hebelomatis calyptrosporum (Bruchet) Locq., Flore mycologique 3: 146 (1979) [MB#314986]